Gas tube relay circuits



May 30, 1944. H. B. DEAL 2,349,849

GAS TUBE RELAY CIRCUIT Filed March l5, 1942 INVENTOR /90//770/75 a/Patented May 30, 1944 :Maus

oas 'was naar cnwurrs naman a. ma. cien anice. N. J., mmm t RadioCorporation of Ameri of Delaware ca,aeorporatlon Application March 13.1942, Serial No. 434,510

:Claima My present invention relates to gas tube relay circuits, andmore particularly to relay control circuits utilizing a low! pressuregas tube of the cold cathode type.

One of the main objects of my present invention is to improve generallythe simplicity and reliability of relay control circuits, and moreespecially to provide a relay control circuit employing a gas triodewhose discharge i; dependent upon the division of voltage across apotential divider connected between the-plate and cold cathode of thetriode and across the source of energizing voltage.

The novel features which I believe to be char acteristic of my inventionare set forth with particularity in the appended claims; the inventionitself, however, as to both its organization and method ci operationwill best be understood by reference to the following description takenin connection with the drawing in which I have indicateddiagrammatically several circuit organizations whereby my invention maybe carried into effect.

In the drawing:

Fig. 1 shows a circuit embodying my invention, the voltage divider beinggenerically represented,

Figs. 2 to 5 inclusive illustrate respectively different modications of'the potential divider,

Figs. 6 and 6a show two further types of potential dividers,

Figs. '1 and 'la illustrate two additional forms of potential dividers.

Referring now to the accompanying drawing, wherein like referencecharacters in the diiierent figures designate similar circuit elements,vthe tube i is generally an ionic-cathode, glow-discharge tube. Itcontains a plate, or anode, 1', a grid, or starter anode, 3 and a coldcathode l. The tube, as shown, is a gas triode of the OA4-G type. Theelectrodes are sealed in a bulb filled with an inert gas or vapor atreduced pressure. The invention is not restricted to this typeoi'f coldcathode relay tube. Indeed, any cold cathode gas tube may be utilized,so long as the plate is enabled to carry current upon dischargeoccurring in the tube in response to the control electrodel 3 assuming astriking" potential.

The energizing voltage source, shown by way of illustration asv of 110volts and 60 cycles,'feeds lines 5 and 6. The cathode l is connected toone side of the energizing system, say line i. The line 5 is connectedto plate 2 through the winding of electromagnet relay l. Condenser I,across the relay winding, acts as a smoothing condenser. It helps tohold the relay armature in the actuated,

or closed. position without chattering. The armature of the relay isdenoted by numeral 9, and is normally spring-biased out of contact withthe switch contact i0. Hence, closure of switch S-I 0 completes anydesired type of controlled circuit. Thus, the controlled circuit mayinclude a lamp, bell, alarm or indicator; or it may be any controldevice which is to be actuated upon energization of relay 1 to closeswitch Ill- 9. For example, amotor to start a heating system may becontrolled.

'.I'he control circuit comprises a.potential divider Z-Z' connectedbetween the lines 5 and i. The control electrode is connected by leadI'i, preferably terminating in an adjustable tap, to any desired pointalong the dividerl Z-Z. The latter, from a generic viewpoint, consistsof a pair of impedances adapted to develop thereacross a potentialdifference. 'I'he nature of the impedances, the magnitude thereof, andthe positioning of tap Il will determine the "striking.

point oi' the gas tube. In normal operation of the' tube I, a relativelysmall amount oi electrical energy supplied to the control electrode, orstarter-anode, 3 initiates a glow discharge between cathode 4 andelectrode 3. This discharge produces positive ions which assist ininitiating the main discharge between cathode and plate 2. The platecurrent, flowing during the cathode-to plate discharge, energizes thewinding of relay 1 thereby to close switchv I 0 9.

'The tap il, regardless of the nature of the divider impedances, isadjusted to a point such that the starter-anode 3 is maintained at apotential just below that required for break-down. Since the strikingpotentialv of the tube I is obtained irom the division of line voltageat the divider Z-Z', any control that will change the division of thevoltage will strike the discharge between cathode and electrode 3. Thiswill, in turn, release the discharge to the plate 2 which carries aheavy currentv supplied by the power line. Hence, the switch. IO-S willbe closed to complete rthe controlled circuit. The particular virtue ofthis invention is the negligible (or for a capacity divider, zero) powerconsumption in the stand-by, or non-actuated, condition. Filament typesof gas or hard vacuum tubes have been used, but they all requirecontinuous power consumption to the amount of several watts. If thedivider resistance is of the order of 1,000,- 000 ohms the powerconsumption is of the order of milliwatts. Divider resistances of manytimes this value are feasible, so that the power consumption may be inthe orde;` oi' microwatts.

which restores the temperature.

In Fig. 3 the divider consists oi' series con-'- densers C-Ci. The tapII is adjusted between the condensers. The upper capacity Ci could be,for example, a liquid level device whose capacity depends on the heightof a body oi' liquid. It is then arranged that as long as C and C1 havea 'deilnlte magnitude relation, the voltages thereacross will be such asto maintain the electrode 3 just below the striking" potential. Uponcondenser Ci undergoing a change in capacity to change the voltagedivision the tube I will have a discharge to the plate 2. In Fig. 4 itis shown that capacities C-Ci may be replaced by inductors L-Lirespectively. Of course, either section of the divider may be thevariable section.

In Fig. 5 the divider consists of a resistor R in series with the outputelement M of a sound pickup device, such as a microphone. For example,in sound detection work theoutput element M is arranged to cooperatewith resistor R to prevent dischargeoi tube I in the absence 'of sound.A predetermined change in voltage division across R-M results in settingof an alarm device in the controlled circuit.

In Fig. 6 there is shown a potential divider P of resistor form; aselenium cell is connected between the line 5 and tap I I. As is wellknown, the selenium cell is a device whose resistance varies with lightfalling thereon. In the position shown, the balance of P (after properadjlmtment for balance by tap Il) prevents ignition of the gas tube forthe then-prevailing illumination of the cell. Any increase of lightintensity at the cellin eilect raises the 60 cycle voltage dierencebetween the starter-anode and cathode thereby causing dis'- charge tothe plate 2.

Similarly, and as shown in Fig. 6a, for'another setting of tap II andthe positioning of the selenium cell between tap I I and line 6, avoltage just below that on the control electrode which will initiate adischarge is found, under the then-prevailing illuminationoi the cell.In this caseany decrease of illumination on the selenium cell willinitiate a gas tube discharge thereby closing th relay switch Ill-9.

In Fig. '7 there' is shown a circuit wherein a photocell 20 replaces theselenium cell of Fig. 6. The photocell may be of the gas or hard vacuumtypes. The divider P has its slidable tap II arranged in series with aresistor 22 of'about 25 megohms. The resistor 22 has shunting it theAphotocell in series with a resistor 23. 'I'he resistor 2 I, of about 20meghoms, connects the electrede end of resistor 22 to line 6. In Fig.'7a the photocell is connected'across the resistor 2|. The latter is thedark-actuated position of the photocell.` as in the case of the selenium`cell in Fig. 6a. The potentiometer P is adjusted by tap Il to itscritical setting such that an increase in illumination of cell 20initiates discharge in the tube I in the case of Fig. v'1, whereas ladecrease in illumination causes the tube I to discharge in the case ofFig. 7a. Diminlshed sensitivity can be had l ance is in parallel withari element of the resistance divider. If the photocelLresistancechanges,

due to a change in illumination upon it, the resistance `divider ratiois upset. and the trigger anode can then ignite the current-carryingdischarge. The extra resistances in Figs. 'l and 7a represent an actualworking instrument. The ranges of resistance variation in the photocellare very high between light and dark. The additional series and shuntresistances hold these variations within limits so that impracticallylarge divider variations are not required.

Once a gas tube is ignited, there must be a reduction of voltage to avalue below the gas extinction de-ionizing voltage, to shut it oilpreparatory to the next ignitionvcycle. For alternating current thisextinction is attained twice each alternation when the line voltage ismomentarily zero. For direct current (or battery) operation, this maybedone manually, or with a circuit interrupter or by other automaticmeans, as for example a blocking (motor boating) network associated withthe gas tube.

While'I have indicated and described several systems for carrying myinvention into eilect, it will be apparent to one skilled in the artthat my invention is by no means limited to the particular organizationsshown and described, but that Vmany modifications may be made withoutdeparting from the scope of my invention, as set forth in the appendedclaims.

What I claim is:

l. In combination with a source of alternating current energizingvoltage, a potential divider consisting of pure resistance thereacross,a gas discharge tube including a cold cathode. a plate and astarter-anode, a controlled circuit including control means-arranged incircuit with the plate, means connecting the cathode to plate path ofthe tube across said source whereby extinction of the gas tube ignitionis attained tw'ice each alternation'when the alternating source ismomentarily zero, and means free of impedance connecting saidstarter-anode to a predetermined point of said divider such that saidstarter-anode is just below the strikingvvoltage of said tube and saiddivider having such a relatively high resistance magnitudevthat thepower consumption v of the gas tube in non-ignited state is negligible.2. In combination, in a relay control circuit, a controlled circuitincluding as an element thereof a switch device, a relay for controllingsaid switch, a gas tube provided with at least a cold cathode,

`a plate and 4a control electrode, a pair of alter- 'charge betweencathode and plate, and said divider having a section thereof whoseresistance is subject to variation such as to change the volt-d agedivision across the divider and said divider having a resistancemagnitude of the order of one million ohms Athereby to'reduce the powerconsumption of the tube in non-ignited state to a negligible value.

3. In combination with a source of alternatingl current energizingcurrent, a potential divider comprising pure resistance thereacross, agas discharge tube including a cold cathode, a plate and astarter-anode, a controlled circuit includtwice each alternation whenthe alternating source is momentarily zero, and means lsubstantiallyfree of impedance connecting said starteranode to a predetermined pointof said divider such that said starter-anode is Just below the strikingvoltage of said tube, and said divider having a resistance magnitude oi'at least one million ohms thereby permitting said tube 'to consumenegligible power from said source in the l0 open" condition oi thecontrol switch.

HARMON B. DEAL.

